My Inquiry
My Account
Battery Life Calculator
This calculator estimates battery runtime based on battery capacity, load current, usable capacity, and optional battery voltage. It is useful for comparing AA, AAA, lithium-ion, LiPo, 18650, coin cell, and rechargeable battery applications. Actual runtime may vary because battery discharge is affected by chemistry, temperature, load profile, cutoff voltage, and aging.
Input Parameters
Results
Battery life estimates are most accurate when the load current is measured as an average over the real operating cycle. For pulsed or sleep-mode devices, use measured average current instead of peak current.
Equations Used
Usable Capacity:
Usable Capacity (mAh) = Rated Capacity (mAh) × Usable Capacity %
Battery Life:
Battery Life (hours) = Usable Capacity (mAh) / Load Current (mA)
Runtime in Days:
Runtime (days) = Runtime (hours) / 24
Energy Estimate:
Energy (Wh) = Battery Capacity (Ah) × Battery Voltage (V)
Average Power:
Average Power (W) = Battery Voltage (V) × Load Current (A)
Frequently Asked Questions (FAQ)
Q1: What does this battery life calculator do?
It estimates how long a battery can power a device based on capacity and average load current.
Q2: Why is actual battery life different from the calculated result?
Actual runtime depends on battery chemistry, discharge curve, cutoff voltage, temperature, aging, and whether the load is constant or pulsed.
Q3: Should I use peak current or average current?
Use average current. For IoT sensors, wireless devices, and sleep-mode systems, peak current can be much higher than the long-term average current.
Q4: What does usable capacity mean?
Usable capacity is the portion of rated battery capacity that can realistically be used before the device stops operating or reaches its cutoff voltage.
Q5: Can I use this calculator for lithium-ion batteries?
Yes. It can be used for Li-ion and LiPo batteries, but charging limits, protection circuits, cutoff voltage, and discharge rate must still be considered.
Q6: Can I use this calculator for coin cell batteries?
Yes, but coin cells are sensitive to load current. High pulse current can reduce usable capacity and voltage stability, so datasheet pulse limits should be checked.
